Sole leather and process of preparing the same



Patented Dec. 7, 1937 I UNITED, STATES PATENT OFFICE SOLE LEATHER ANDPROCESS OF PREPAR- ING THE SAME Otto Darmstadt, Germany No Drawing.Application June 29, 1936, Serial No. 88,057. In Germany July 2, 1935 6Claims. (01. 149-4) The invention relates to improvements in sole Inorder also to make the exterior of the new leather and the process ofpreparing the same. type of leather simulate bark-tanned leather as Mostsole leathers are nowadays prepared with much as possible, bichromatemay be added to the the aid of vegetable tanning agents. The specialsulphite cellulose extract,- thus producing a properties of bark-tannedsole leather are: limleather having a browncolor. In lieu of bichro- 5ited permeability to air, limited water absorption mate, other oxidationagents may be used. capacity, rapid giving off of water under pressure,limited content of water-soluble substances, and Example definiteSpecific gravity- Furthermore, bark- Hides which have been limed, hated,and pick- 10 tanned leather increases in strength when it is led in theusual manner are fulled in a. barrel 10 rolled under heavy pressure,whereas mineral for two days of eight, hours each t tanned leatherbecomes softer under such treat- Percent me Th s p p t s a of importancein Sulphite cellulose extract of 28-30 B. (calworking up the leather forshoe soles and during ated on the'weight of the hides) 50 the wearing ofthe shoes. During the working Sodium or potassium bichromate 1 15 up ofthe leather the important points are that w te 25 the leather can besewed and nailed, that the nails hold, and that the cut portions can befinished with a nice gloss. Bark-tanned leather produces,

After this period the leathers remain lying on the block for two days.Thereupon they are fulled for two days ofeight hours each with:

as the worker in the art says: a good finished 2 trim. When being worn,the properties are man- Percent o ifested by the fact that the wearerdoes not skid sulPmte cellulose F fi of B 50 on bark-tanned soles in wetweather, and that sodmm Potasslum bmhmmate 1 the soles, when they becomewet, do not swell water 25 25 and thus alter the Shape of the shoes'After storing for two days the leathers are fulled In order first toshorten the duration of the for four hours with a solution of:

tanmng process and, secondly, in order to be in- Percent dependent ofthe importation of foreign vegetable Formic acid (85% tanmng agents, theworkers in the art have for waterglass solution having 25% sioz 10 manyyears attempted to substitute mineral tan- Water i 15 3o ning agents forvegetable tanning agents in the preparation of sole leather, but withoutappreciuntil all of the liquor is taken p- The a e s able success. arestored overnight on the block.

The reason for the lack of success is that the N morning a mixture of pfl P1115 vegetable tanning agents impart the above recit d 2.5% tetralinis fulled into the leather while in the 35 special properties to theleather and these results greasing V The leathers. which h e cannot beachieved with the mineral tanning stored on the floor over ni t a e la dout the agents. Even sulphite cellulose extracts have n xt m n d dWorking up p ds in been tried and have been mixed with i l the same wayas in the case of bark-tanned sole 40 tanning agents but withoutresult.- leather. 40

- It ha be n found that a ol l th can be According to the above recitedprocess oxidizobtained in a few days by using a, c mbi ti ing agentssuch as bichromate are described as employing sulphite celluloseextract, acidified 51- -used together with the sulphite celluloseextract,

licic acid solution and a small amount of fatty and the pr s so arrangedh he lea hers are substances and that such leather possesses all fu ed wt ac d silicic d s o I 45 of the properties of bark-tanned leather. TheIt has alsobeen found that a greatly improved chemicals required inproducing this leather need sole leather is obtained if the silicic acidis not not be imported from abroad. used subsequently but rather, undercertain con- The method is as follows: ditions, along with the sulphitecellulose tanning The hides, cleaned as usual, are fulled withsulprocess and in such fashion that the hides are 50 phite celluloseextract, then treated with an acidfirst treated with a sulphitecellulose extract ified alkali silicate solution and impregnated withliquor. without addition of silicic acid and then a. little hard greasesuch as tallow, paraflin, carfirst with sulphite cellulose liquorcontaining nauba wax, synthetic waxes, etc., with or without addedsilicic acid. Immediately thereupon the the addition of solvents.leathers are filled with silicic acid solution as de- 55 with hardgreases or waxes or, prior to drying, r

they may merely be oiled with neats-foot oil.

The process may with advantage be supplemented by adding small amountsof othertanning agents, such as alum tanning agents, chrome tanningagents, vegetable tanning agents, or synthetic tanning agents, in orderto vary the basic character of the leather.

Examples 1. l-Iides which have been limed, hated, and pickled as usualare fulled in a barrel for two days of eight hours each in:

Percent Sulphite cellulose extract of 28-30 B. (calculated on hideweight) Water- 25 After this time the leathers remain lying on the blockfor two days. Thereupon they are again, fulled for two days of eighthours each in a fresh liquor of Percent Sulphite cellulose extract (of28-30 B.)--- 50 Concentrated formic acid 2 Waterglass solution having25% S10: 10 Water 25 After storing for two days the leathers are fulledfor 1 to 2 hours with a solution of:

until all of the liquor is taken up. The leathers are stored over nighton the block. This fulling may be repeated 1 or 2 times. After the lastfulling the leathers are again stored over night on the block; and thenext morning washed off on both sides with water, laid out, and oiledwith neat s-foot oil on the grain side.

2. The procedure is that as given in Example 1, with the feature that inpreparing the 1st and 2nd tanning liquors 1.5% of chrome alum is added.A sole leather of pleasant color shade is obtained.

3. The procedure is that as given in Exa le. 1, with the feature that inpreparing the 1s and 11d a ing iq ors. p tash alum is added.

A rapid, thorough tanning results and the leather produced has goodquality and good tearing strength;

4. The procedure is that as given in Example 1, with the feature that inpreparing the 1st and 2nd tanning liquors, 10% aluminum formate isadded. An especially water-resistant leather is obtained.

5. The procedure is that as given in Example 1, with the feature that inpreparing the 1st and 2nd tanning liquors, 1% of commercial synthetictanning agent is added, such as a condensation product of naphthalenesulphonic acid and formaldehyde.

The invention has been described in detail for the purpose ofillustration but it will be apparent that modifications or variations ofthe process may be resorted to without departing from the spirit of theinvention claimed.

I claim:

1. A process for preparing sole leather which comprises first tanninghides with sulphite cellulose extract before any silicic acid is added,and in a subsequent step filling with silicic acid solution.

2. A process for preparing sole leather which comprises first tanninghides with sulphite cellulose extract before any silicic acid is added,and in a subsequent step filling with silicic acid solution, andtreating with a member of a group consisting of oils, greases, andwaxes.

3. A process for preparing sole leather which comprises first tanninghides with sulphite cellulose extract and an-oxidizing agent before anysilicic acid is added and in a subsequent step filling with silicic acidsolution.

4. A process as set forth in claim 3, wherein the oxidizing agent is amember of a group consisting of sodium bichromate and potassiumbichromate.

5. A process for preparing sole leather which comprises first tanninghides with sulphite eellulose extract before any silicic acid is added,then treating with sulphite cellulose extract and silicic acid solution-6. A process for preparing sole leather which comprises first tanninghides with sulphite cellulose extract before any silicic acid is added,then treating with sulphite cellulose extract and silicic acid solution,and in a subsequent step filling with silicic acid solution.

OTTO RHlVI.

